This invention relates to air cushion supported marine vehicles such as are referred to as "surface effect ships" (SES). The invention provides an improvement in respect to the prior type air cushion seals employed at the stern ends of such vessels, which have in the past typically employed a plurality of side-by-side vertically disposed air-inflated "fingers" extending between the opposite sidehulls of the ship. Examples of such prior art are disclosed in U.S. Pat. Nos. 3,260,323; 3,297,102; 3,372,664; 3,420,330; 3,443,659; 3,756,343 and 3,907,061. Such seal systems may comprise any number of segments or fingers arranged in side-by-side relation; and in any case they individually depend from the hull structure of the ship so as to bridge across the stern end of the air cushion space beneath the ship.
However, in the case of stern seals of the type shown in the above referenced patents, the anti-scooping protective sheets thereof tend to locally distort especially under severe operating conditions, and therefore generate drag and occasionally permit the fingers to ingest water from the traveling surface, thereby impeding operation of the ship. It is an object of the present invention to provide for a SES an improved stern seal system which minimizes the possibility of such undesirable occurrences under typical operating conditions, and to more readily off-load any water scooping loads such as may occur.
Buffeting wear and tear effects on the water-wave contact portions of the fingers of such seals require that for continuing efficient operations of the ship the fingers thereof need be repaired or replaced from time to time, depending upon the severities of service imposed thereon. Therefore, another object of the invention is to provide a stern seal construction as aforesaid wherein the fingers thereof are less subject to flagellation forces and are more readily serviceable while the vessel is standing in water. Still another object is to provide an improved finger construction as aforesaid whereby the flexible fabric material thereof is substantially free from operating local stress concentrations, such as is especially important when operating under high speed rough water conditions. The present invention provides a finger construction of such nature that its local geometry allows the fabric thereof to take on a truly ideally inflated configuration, without any localized buckling and/or distortions thereof. Thus, rapid wear problems such as have haunted prior art designs of such fingers are avoided. Other objects and advantages of the invention will appear from the description hereinafter.